1. Field
The disclosure relates to a method, system, and article of manufacture for performing stating or destaging based on the number of waiting discard scans.
2. Background
A storage controller may be coupled to one or more of a plurality of hosts. The storage controller may manage a plurality of storage devices, such as disk drives, tape drives, etc., that are coupled to the storage controller. The plurality of hosts may access data stored in the storage devices via the storage controller.
The storage controller may maintain a cache, where a cache is a type of storage that is capable of providing faster access to data in comparison to storage devices such as disk drives or tape drives. The storage space provided by the cache is smaller in size than the storage space provided by the disk drives or tape drives, where the storage provided by the disk drives or tape drives, and other devices, may be referred to as secondary storage. As a result, tracks may need to be staged (i.e., moved to the cache from secondary storage) or destaged (i.e., moved from the secondary storage to the cache) to prevent the cache from becoming full and to provide faster access to data. In many situations, to release space in the cache, tracks may be discarded from the cache via discard scans.
A “Task Control Block” (TCB) is a data structure in the operating system kernel containing the information needed to manage a particular process. Storage controllers may move information to and from storage devices, and to and from the cache by using TCBs to manage the movement of data.